Methods of applying a protective barrier to the liner of an explosive charge

ABSTRACT

According to an embodiment, a method of protecting at least a liner of an explosive charge from an environment comprises: applying a material onto or adjacent to the liner of the explosive charge, wherein prior to the step of applying, the liner is capable of being exposed to the environment, and wherein the material is capable of providing a protective barrier to at least the liner against the environment.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to PCT Application No. PCT/US12/35269, filed on Apr. 26, 2012.

TECHNICAL FIELD

Methods of applying a material onto or adjacent to the liner of a charge are provided. The charge can be an open-faced shaped charge. The liner, prior to application of the material can be capable of being exposed to an environment. The environment can include components that are capable of degrading the liner. The material can create a protective barrier to the liner such that if the liner is exposed to an environment containing such components, then the liner of the charge is not degraded.

SUMMARY

According to an embodiment, a method of protecting at least a liner of an explosive charge from an environment comprises: applying a material onto or adjacent to the liner of the explosive charge, wherein prior to the step of applying, the liner is capable of being exposed to the environment, and wherein the material is capable of providing a protective barrier to at least the liner against the environment.

BRIEF DESCRIPTION OF THE FIGURES

The features and advantages of certain embodiments will be more readily appreciated when considered in conjunction with the accompanying figures. The figures are not to be construed as limiting any of the preferred embodiments.

FIG. 1 depicts a material applied adjacent to the liner of an open-faced charge.

FIG. 2 depicts a material applied onto the liner of the charge according to an embodiment.

FIG. 3 depicts a material applied onto the liner of the charge according to another embodiment.

DETAILED DESCRIPTION

As used herein, the words “comprise,” “have,” “include,” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

Shaped charges are used in a variety of applications, such as military and non-military applications. In non-military applications, shaped charges are used: in the demolition of buildings and structures; for cutting through metal piles, columns and beams; for boring holes; and in steelmaking, quarrying, breaking up ice, breaking log jams, felling trees, and drilling post holes. Another common non-military application is the oil and gas industry.

In the oil and gas industry, shaped charges can be used to increase the permeability of a subterranean formation. Well perforation operations can involve the controlled detonation of shaped charges within the well. The shaped charges perforate the casing, if any, and the surrounding formation, thereby improving the flow of liquids into or from the wellbore. A perforation gun is used to hold the charges. The perforation gun is lowered into the well on either tubing or a wire line until it is at the desired depth within the formation. The gun assembly includes a charge holder that holds the shaped charges, and a detonation cord links each charge located in the charge holder.

A shaped charge generally includes a conically-shaped charge case, a solid explosive load, a liner, a central booster, array of boosters, or detonation wave guide, and a hollow cavity forming the shaped charge. If the hollow cavity is lined with a thin layer of metal, plastic, ceramic, or similar materials, the liner forms a jet when the explosive charge is detonated. Upon initiation, a spherical wave propagates outward from the point of initiation for the basic case of a single point initiated charge, initiated along the axis of symmetry. This high pressure wave moves at a very high velocity, typically around 8 kilometers per second (km/s). As the detonation wave engulfs the lined cavity, the liner material is accelerated under the high detonation pressure, collapsing the liner. During this process, for a typical conical liner, the liner material is driven to very violent distortions over very short time intervals (microseconds) at strain rates of 104 to 107/s. Maximum strains greater than 10 can be readily achieved since superimposed on the deformation are very large hydrostatic pressures (peak pressures of approximately 200 gigapascals “GPa” (30 million pounds force per square inch “psi”), decaying to an average of approximately 20 GPa). The collapse of the liner material on the centerline forces a portion of the liner to flow in the form of a jet where the jet tip velocity can travel in excess of 10 km/s. The conical liner collapses progressively from apex to base under point initiation of the high explosive. A portion of the liner flows into a compact slug (sometimes called a carrot), which is the large massive portion at the rear of the jet.

Liners can be made from a variety of materials, including various metals and glass. Common metals include copper, aluminum, tungsten, tantalum, depleted uranium, lead, tin, cadmium, cobalt, magnesium, titanium, zinc, zirconium, molybdenum, beryllium, nickel, silver, gold, platinum, and pseudo-alloys of tungsten filler and copper binder. The selection of the material depends on many factors including economic drivers as well as performance requirements. For example, a copper and lead powdered matrix pressed into a final geometric form has been found to work well for the oil and gas industry historically with higher performance embodiments comprising increasing amounts of tungsten powder within the metal matrix.

The liner of open-face charges (i.e., charges where the liner is exposed), for example a shaped charge, can be susceptible to degradation from exposure to the environment. Such exposure can occur, for example, during storage of the charge prior to use. The charge can be exposed to liquids, such as rain water during storage. The environment can also contain harmful components, for example, there can be moisture present at the storage location. In this example, the liner can absorb the water molecules contained in the air. The absorbed water molecules can cause degradation of the liner, and thus, affect the performance of the charge. Oxygen in the environment can also degrade the liner. Moreover, if the liner is made from a metallic element, then the presence of oxygen and moisture in the air can cause the liner to oxidize, also degrading the liner and negatively impacting the performance of the charge.

Thus, there is a need to protect the liner of a charge from the environment such that the performance of the charge is not compromised due to environmental effects. The liner needs to be protected from the environment during transportation and storage of the charge. The liner also needs to be protected after partial or full assembly into a device and prior to detonation of the charge.

A novel method of protecting the liner of a charge includes applying a protective material directly onto or adjacent to the liner. The protective material can create a hermetic seal, such that the exposure of the liner to detrimental components in the environment is substantially reduced and preferably eliminated.

According to an embodiment, a method of protecting at least a liner of an explosive charge from an environment comprises: applying a material onto or adjacent to the liner of the explosive charge, wherein prior to the step of applying, the liner is capable of being exposed to the environment, and wherein the material is capable of providing a protective barrier to at least the liner against the environment.

The Figures depict an example of an explosive charge 100. The charge can be a shaped charge. The charge 100 can include a charge case 101. The charge case 101 can be conical or pyramidal in shape. The charge case 101 can include an apex and a base. The apex can be truncated. The charge 100 can include an explosive load 102. The explosive load 102 can be located within and adjacent to the charge case 101. The charge 100 also includes the liner 103. The liner 103 can be positioned adjacent to the explosive load 102. In this manner, the liner is adjacent to the explosive load and then the explosive load is adjacent to the charge case. The liner 103 can be conical or pyramidal in shape. The liner 103 can be made from a variety of materials, including, but not limited to, glass, copper, aluminum, tungsten, tantalum, depleted uranium, lead, tin, cadmium, cobalt, magnesium, titanium, zinc, zirconium, molybdenum, beryllium, nickel, silver, gold, platinum, and pseudo-alloys of tungsten filler and copper binder. The charge 100 can also include a detonator, a seal disc 105, and a booster charge 106. The detonator can be part of a detonation cord 104.

The charge 100 can include a hollow cavity (not labeled) on the inside of the charge. The liner 103 can include a portion that borders the explosive load 102 and another portion that borders the hollow cavity. According to an embodiment, prior to the step of applying, the liner 103 is capable of being exposed to the environment. As used herein, the term “environment” means the surroundings of an object. According to another embodiment, prior to the step of applying, the portion of the liner 103 that borders the hollow cavity is capable of being exposed to the environment. The charge 100 can be an open-faced charge. Examples of open-faced charges include, but are not limited to, deep-penetrating (DP) charges, big hole (BH) charges, Good Hole (GH) charges, Frac Charges, reactive liner charges and other embodiments designed to suit specific performance objectives generally referred to as rock optimized charges.

According to an embodiment, the environment contains at least one component that is capable of degrading at least a portion of the liner 103. As used herein, the term “degrade” and all grammatical variations thereof, means to negatively affect intended performance, make smaller or break up into smaller components or fragments. For example, the environment can comprise moisture. As used herein, the term “moisture” means the presence of a liquid, for example water, in air. By way of another example, the environment can comprise oxygen gas. The environment can contain both, moisture and oxygen gas. It is to be understood that the environment does not have to contain a component capable of degrading the liner; however, the material can form the protective barrier such that if the environment does contain one or more components capable of degrading the liner, then the liner is at least partially, and preferably fully, protected from degradation by the components. Moreover, it is to be understood that depending on the substance that the liner is made from, the component(s) that is capable of causing degradation of the liner will vary. Therefore, moisture and oxygen gas are not the only possible components that are capable of causing degradation of the liner.

The methods can further include the step of manufacturing the charge. The methods can also include the step of removing components capable of causing degradation to the liner during the step of manufacturing, prior to the step of applying, and during the step of applying. For example, moisture and oxygen gas can be removed from the area. Removal of oxygen gas can be accomplished for example, by having only nitrogen gas or an inert gas, such as helium or argon in the area. The methods can also include the step of partially or fully assembling the charge into a device, such as a perforation gun, after the step of applying and/or cooling the material or allowing the material to cool.

The methods can further include the step of placing the charge in an enclosure after the step of applying. If the material solidifies via a decrease in temperature, then the step of placing can be performed after the step of cooling or allowing the material to cool. The charge can also be vacuum sealed in the enclosure, such that harmful components are not trapped within the enclosure. The charge can be stored in the environment for a specified period of time. The period of time can be a time such that the liner, without the material, is capable of being at least partially degraded by one or more components of the environment.

The methods include the step of applying a material onto or adjacent to the liner 103. According to an embodiment, the material 201, 202, 203 is capable of providing a protective barrier to at least the liner 103 against the environment. The material 201, 202, 203 can also provide a protective barrier to the liner 103 and the explosive load 102. According to an embodiment, the material 201, 202, 203 is selected such that one or more components capable of causing degradation to the liner 103 (e.g., moisture and/or oxygen gas) is prevented from penetrating the material.

FIG. 1 depicts a method of applying the material according to an embodiment. As can be seen, FIG. 1 depicts an example of the material applied adjacent to the liner. According to this embodiment, the step of applying can comprise applying the material 201 to the base of the charge case 101. The material can be a solid during and after the step of applying. The material 201 can be circular in shape. For example, the material 201 can be a solid, circular disc.

The material 201 can further comprise an adhesive (not shown). The adhesive can be located on one side of the material 201. The adhesive can be located around the perimeter of the material 201. The adhesive can have a height such that at least a portion of the thickness (i.e., the difference between the inner diameter and the outer diameter) of the base of the charge case 101 can be contacted by the adhesive. According to an embodiment, the adhesive has a height greater than or equal to the thickness of the base of the charge case 101. In this manner, the adhesive can completely cover the entire thickness of the base of the charge case 101. The step of applying can comprise affixing the adhesive to the base of the charge case 101. The step of affixing can include using a pressure to secure the material to the charge case. The pressure can be a mechanical pressure or hand pressure.

The adhesive can be permanent or removable. If the adhesive is permanent, then once the material 201 is applied to the base of the charge case 101, the material is not easily removed from the charge case. For example, during assembly of the charge and/or during positioning of the charge at the desired detonation location, the material does not become removed from the charge case. However, it is to be understood that the use of the word permanent does not imply that at least a portion of the material is never removed from the charge case because in an embodiment, the material does not substantially interfere with the functioning of the charge. In this example, during the actual detonation of the explosive load, at least some or all of the liner should be removed from the charge case. If the adhesive is removable, then preferably the material 201 is removed from the charge case 101 prior to use of the charge. The material 201 can be removed via a person. If the adhesive is removable, then preferably the adhesive secures the material 201 to the charge case 101 until such a time as it is desirable to remove the material. For example, the adhesive should be strong enough that the material does not easily fall off of the charge case, but rather, requires some force for removal.

FIG. 2 depicts a method of applying the material according to another embodiment. As can be seen, FIG. 2 depicts an example of the material 202 being applied onto the liner 103. The step of applying can also comprise applying the material 202 to the portion of the liner 103 that borders the hollow cavity of the charge. The step of applying can comprise the step of spraying the material 202 onto the liner 103. According to this embodiment, the material 202 is sprayed onto the portion of the liner 103 that borders the hollow cavity of the charge 100 such that the entire exposed surface of the liner 103 is covered by the material 202. The material 202 can be selected such that it is capable of being applied to the liner 103 via a spraying apparatus. Spraying apparatuses are known in the art, and one can select the exact spraying apparatus and pressure of the spray based on the material 202 selected. The material 202 that is sprayed onto the liner 103 can be sprayed such that a layer of the material coats the liner. According to this embodiment, the material 202 can be a liquid that is sprayed onto the liner. The liquid material 202 can then solidify after the spray application to create the protective barrier. The liquid material can solidify based on a change in temperature. For example, the liquid material can be heated prior to application, and then once applied onto the liner, the material can be cooled or allowed to cool in order for the material to solidify. Examples of materials that are capable of solidifying when cooled include, most metals, plastics, compounds undergoing a phase change (e.g., from a liquid to a solid), and compounds that are malleable near ambient temperatures (71° F.), such as wax.

As depicted in FIG. 3, the material 203 that is sprayed onto the liner can also be a foam. As used herein, the term “foam” means a colloid that comprises a continuous liquid phase (the external phase) and a gas as the dispersed phase (the internal phase). According to this embodiment, the external phase can be a liquid during the application of the material. The liquid external phase can then solidify after application to create the protective barrier. The liquid external phase can be selected such that after curing, the liquid becomes a solid. As used herein, the term “cure” and all grammatical variations thereof, means the process of becoming hard or solid via heat. According to an embodiment, the permeability of the foam is sufficiently small such that components in the environment capable of degrading the liner are not able to penetrate through the foam and come in contact with the liner 103.

According to an embodiment, the material 201, 202, 203 is selected such that the material is compatible with the explosive load 102. For example, the material 201, 202, 203 can be selected such that the material does not degrade the explosive load 102. According to an embodiment, the thickness of the material 201, 202, 203 is selected such that one or more components capable of causing degradation to the liner 103 (e.g., moisture and/or oxygen gas) is prevented from penetrating through the material and coming in contact with the liner 103. According to another embodiment, the thickness of the material 201, 202, 203 is selected such that the functioning of the charge is not impaired. For example, the thickness of the material can be selected such that the high-energy jet of metal fragments and energy during detonation of the charge is not impeded. The material can have a thickness in the range of about 1 to 10,000 micrometers (μm). As described in reference to FIG. 1, the material 201 can have a thickness in the range of about 20 to about 500 μm. As described in reference to FIG. 2, the material 202 can have a thickness in the range of about 1 to about 25 μm. As described in reference to FIG. 3, the material 203 can have a thickness in the range of about 500 to about 10,000 μm. Moreover, with reference to FIG. 3, the material 203 can completely fill the hollow cavity of the charge 100. The exact thickness of the material 201, 202, 203 can vary and can depend on a variety of factors including, but not limited to, the type of substance the material is made from, method of application, intended product life and size of explosive charge applied to, and the quantity of the explosive load.

According to yet another embodiment, the material 201, 202, 203 is capable of withstanding the anticipated temperature changes of the environment. For example, it is not uncommon for a charge 100 to be stored in an environment where temperature changes occur. If the temperature changes are significant, then the material can crack or become weakened via expansion and contraction of the material during the temperature change(s). Moreover, depending on the exact substance that the material is made from, the material may undergo a phase change from a solid to a liquid; thus, the material may no longer form the protective barrier to the liner. For example, a wax, when heated beyond its transition temperature can expand and become less viscous.

Examples of materials 201 capable of being applied adjacent to the liner as depicted in FIG. 1 include, but are not limited to: a polymer, such as MYLAR® polyester film, and KAPTON® polyimide film, available from DuPont in Circleville, Ohio, polyamide films, polymer tapes, foil tapes, polyesters, and ceramic tapes; and metals, such as aluminum and aluminum foil tape. Examples of materials 202 capable of being applied onto the liner as depicted and described in reference to FIG. 2 include, but are not limited to, paint compositions, silicon based paints and coatings, polyurethanes, synthetic resins, conformal coatings, nanotechnology coatings, etc. Examples of materials 203 capable of being applied onto the liner as depicted and described in reference to FIG. 3 include, but are not limited to, synthetic closed cell foams and compounds, silicon foams and compounds, syntactic foams and compounds, and rubber foams and compounds.

Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is, therefore, evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods also can “consist essentially of” or “consist of” the various components and steps. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a to b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 

What is claimed is:
 1. A method of protecting at least a liner of an explosive charge from an environment comprising: applying a material onto or adjacent to the liner of the explosive charge, wherein prior to the step of applying, the liner is capable of being exposed to the environment, and wherein the material is capable of providing a protective barrier to at least the liner against the environment.
 2. The method according to claim 1, wherein the charge is a shaped charge.
 3. The method according to claim 1, wherein the liner is made from a substance selected from the group consisting of glass, copper, aluminum, tungsten, tantalum, depleted uranium, lead, tin, cadmium, cobalt, magnesium, titanium, zinc, zirconium, molybdenum, beryllium, nickel, silver, gold, platinum, pseudo-alloys of tungsten filler and copper binder, and combinations thereof.
 4. The method according to claim 1, wherein the charge further comprises a charge case, an explosive load, and a hollow cavity, wherein the explosive load is located within and adjacent to the charge case, and wherein the liner is positioned adjacent to the explosive load.
 5. The method according to claim 4, wherein charge case is pyramidal or conical in shape and wherein the step of applying can comprise applying the material to the base of the charge case.
 6. The method according to claim 5, wherein the material is a solid prior to and during the step of applying.
 7. The method according to claim 6, wherein the material further comprises an adhesive.
 8. The method according to claim 1, wherein the step of applying comprises the step of spraying the material onto the liner.
 9. The method according to claim 8, wherein the material is selected such that it is capable of being applied to the liner via a spraying apparatus.
 10. The method according to claim 9, wherein the material is a liquid or a foam during the step of applying.
 11. The method according to claim 10, wherein the liquid portion of the material solidifies after the step of applying.
 12. The method according to claim 1, wherein the environment contains at least one component that is capable of degrading at least a portion of the liner.
 13. The method according to claim 12, wherein the material and the thickness of the material are selected such that the component is prevented from penetrating the material.
 14. The method according to claim 1, wherein the material is selected such that the material is compatible with the explosive load.
 15. The method according to claim 1, wherein the thickness of the material is selected such that the functioning of the charge is not impaired.
 16. The method according to claim 1, wherein the material is selected from the group consisting of a polymer, polyester films, polyimide films, polyamide films, polymer tapes, foil tapes, polyesters, ceramic tapes, metals, such as aluminum and aluminum foil tape, paint compositions, silicon based paints and coatings, polyurethanes, synthetic resins, conformal coatings, nanotechnology coatings, synthetic closed cell foams and compounds, silicon foams and compounds, syntactic foams and compounds, rubber foams and compounds, and combinations thereof.
 17. The method according to claim 1, further comprising the step of manufacturing the charge.
 18. The method according to claim 1, further comprising the step of removing components capable of causing degradation to the liner prior to the step of applying and during the step of applying.
 19. The method according to claim 1, wherein the methods can also include the step of partially or fully assembling the charge into a device after the step of applying.
 20. The method according to claim 1, further comprising the step of placing the charge in an enclosure after the step of applying. 